I've been vaguely watching the same models as a potential replacement for Mrs D's touring. If the budget can stretch a little further and he's willing to consider petrol (not necessarily a bad thing to do since its likely that the cost effectiveness of diesels will change in the next few years as fuel duty, road tax and VRT policy evolves against them) then it could be worth taking look at 2016 A4 1.4 TFSI Sport Avant's in the UK. These are the latest model and with a relatively modest mileage they should be landed for ~€22k. It would avoid the risk of timing chain issues with an F31 of the age of your example and CO2 still leaves it in the €280 road tax category.

https://www.autotrader.co.uk/classif...e=60000&page=1